I downgraded my laptop tonight, and now I can't get the NIC driver to get online?

Okay so the laptop I got had Vista on it, and I wanted to put XP on it, so I did. Well now I go to compaq, and pick the OS as XP, and nothing on there is installing on the laptop. So maybe if someone has link, or would happen to know what I am doing wrong. I mean I know how to get around on a computer, but I struggle with the loading of drivers after formatting the HD. If ya need more info just let me know.